Question:

The 2SK1522E datasheet states a drain peak current of 200 A at "PW ≤ 10 μs, duty cycle ≤ 1%". What does this mean?

Answer:

PW ≤ 10 μs, duty cycle ≤ 1% means that (a) during 1% (or less) of one cycle, (b) a pulse of pulse width 10 μs (or less) is applied. This means that for the 2SK1522E, under these conditions and at the rated channel temperature, the maximum drain current is 200 A.